Downlink data notification message sending method, and apparatus

ABSTRACT

A downlink data notification message sending method and apparatus are disclosed. In an embodiment a method includes receiving, a delay instruction from a mobility management network element, which is used to instruct a control plane network element to delay sending a DDN message, receiving, an event report message includes a reported event from a user plane network element, and the reported event is used to notify the control plane network element that a downlink data packet sent to UE matches no bearer, determining, that the UE is registered in the mobility management network element, and if the control plane network element has not received, within a first time period, routing information of a base station, sending, the DDN message to the mobility management network element when the first time period expires.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/451,609, filed on Jun. 25, 2019, which is a continuation of U.S.patent application Ser. No. 16/009,828, filed on Jun. 15, 2018, now U.S.Pat. No. 10,362,557, issued on Jul. 23, 2019, which is a continuation ofInternational Application No. PCT/CN2015/097733, filed on Dec. 17, 2015.All of the a fore-mentioned patent applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

Embodiments of the present invention relates to the communicationsfield, and in particular, to a downlink data notification (DDN) messagesending method, and an apparatus.

BACKGROUND

In an evolved packet system (EPS) network, as shown in FIG. 1, a controlplane function and a user plane function are integrated in both aserving gateway (SGW) and a packet data network gateway (“PDN GW” or“PGW”), and the serving gateway and the packet data network gatewaymainly participate in mobility management and session management, forexample, access control, data forwarding, and charging. For idle-stateuser equipment (UE), because there is no user plane S1 path (in otherwords, S1-U path) or radio bearer, the UE cannot send an uplink datapacket to the network, and when the SGW receives a downlink data packet,the SGW cannot send the downlink data packet to the idle-state UEeither. When the SGW receives the downlink data packet and detects thatthe UE is in an idle state, in other words, there is no S1-U path orradio bearer, the SGW sends a downlink data notification (DDN) messageto a mobility management entity (MME), and triggers the MME to startpaging the UE. After receiving a paging message, the UE initiates aservice request procedure, to request to establish an S1-U path and aradio bearer.

For the MME, there are not many DDN messages for single UE registered inthe MME. However, usually, at least tens of thousands of UEs areregistered in one MME, and when there are a plurality of idle-state UEsin all UEs registered in the MME, the SGW sends a plurality of DDNmessages to the MME, causing a great signaling load to the MME. In acurrent system art, if an MME requests an SGW to delay sending a DDNmessage, the MME sends a downlink packet delay notification request tothe SGW in a service request procedure initiated by UE. After receivingthe request of the MME, if subsequently receiving downlink data ofidle-state UE registered in the MME, the SGW no longer directly sends aDDN message to the corresponding MME, but sets a timer based on therequest of the MME, to buffer the received downlink data.

With evolution of network architectures, an architecture based on adistributed gateway (DGW) is an enhanced network architecture proposedbased on an existing EPS network architecture and based on an idea ofcontrol/user (C/U) separation of a network function. The C/U separationrefers to decoupling a control plane function and a user plane functionof a gateway, and the enhanced network architecture includes a controlplane gateway (CGW) and a user plane gateway (UGW). The DGW is adistributed UGW. The CGW is a centralized control plane gateway,integrates control plane functions of an SGW and a PGW in an EPSnetwork, and is configured to process control plane signaling. The DGWintegrates user plane functions of the SGW and the PGW in the EPSnetwork, and is configured to process user plane data. The DGWimplements user plane data processing, for example, user data packetforwarding, under control and management of the CGW. When a downlinkdata packet of idle-state UE received by the DGW matches no S1-U path orradio bearer, the DGW reports the event to the CGW, to trigger the CGWto send a DDN message to an MME, so that the MME starts to page the UE.However, in an architecture of the distributed gateway, a user planegateway is at a relatively low location, and is deployed in a locationrelatively close to UE, and a service range of the user plane gateway isfar smaller than a service range of the MME. Therefore, all UEs in oneMME may connect to a plurality of different user plane gateways.Delaying a DDN message is an MME-based granularity operation, and forone user plane gateway, UE served by the user plane gateway may beregistered in a plurality of MMEs. However, in a case of C/U separation,the user plane gateway is unaware of an MME in which the UE isregistered. Therefore, in the case of C/U separation, how to send a DDNmessage is a problem urgently to be resolved.

SUMMARY

Embodiments of the present invention provide a DDN message sendingmethod, an apparatus, and a system, so that DDN message sending can becompleted in a case of C/U separation.

According to one aspect, an embodiment of the present invention providesa DDN message sending method. The method includes receiving, by acontrol plane network element, a delay instruction sent by a mobilitymanagement network element, where the delay instruction is used toinstruct the control plane network element to delay sending a DDNmessage. The method also includes receiving, by the control planenetwork element, an event report message sent by a user plane networkelement, where the event report message includes a reported event, andthe reported event is used to notify the control plane network elementthat a downlink data packet sent to UE matches no bearer. The methodalso includes determining, by the control plane network element, thatthe UE is registered in the mobility management network element. Themethod also includes, if the control plane network element has notreceived, within a first time period, routing information of a basestation sent by the mobility management network element, sending, by thecontrol plane network element, the DDN message to the mobilitymanagement network element when the first time period expires, where therouting information of the base station is used to identify a bearer.

Therefore, the control plane network element can determine, based on theevent report message reported by the user plane network element, themobility management network element in which the UE is registered, sothat processing complexity of the user plane network element is lowered.Further, after receiving the delay instruction sent by the mobilitymanagement network element, if the control plane network element has notreceived the routing information of the base station within the firsttime period, the control plane network element sends the DDN message tothe mobility management network element only when the first time periodexpires, so that DDN message sending is reduced, and signaling load ofthe mobility management network element is reduced.

In a possible design, the event report message further includesidentifier information, and the identifier information is used todetermine that the downlink data packet is sent to the UE; and thedetermining, by the control plane network element, that the UE isregistered in the mobility management network element includes:determining, by the control plane network element based on theidentifier information and locally stored context information of the UE,that the UE is registered in the mobility management network element.Therefore, the control plane network element can rapidly and accuratelydetermine, based on the identifier information, the corresponding UE forwhich DDN message sending needs to be delayed.

In a possible design, the delay instruction includes a delay parameter,and after the determining, by the control plane network element, thatthe UE is registered in the mobility management network element, themethod further includes: starting, by the control plane network element,a first timer based on the delay instruction, and configuring timedduration of the first timer to the first time period based on the delayparameter; and sending, by the control plane network element, a firstindication message including the first time period to the user planenetwork element that has started a second timer, where timed duration ofthe second timer is a second time period, and the first indicationmessage is used by the user plane network element to restart the secondtimer and configure the timed duration of the second timer to the firsttime period, or is used by the user plane network element to configurethe timed duration of the second timer to a sum of the second timeperiod and the first time period, so that the user plane network elementbuffers a subsequently received downlink data packet. Therefore, a timermechanism is set, so that a delaying time by which DDN message sendingis delayed can be controlled appropriately, and relatively great impactcaused to service experience of a user because a user service cannot beresponded to due to a long time delay can be avoided. Further, a methodfor instructing the user plane network element to reuse the second timeris used, in other words, the timed duration of the second timer isdirectly extended, so that processing complexity of restarting, by theuser plane network element, a timer can be lowered.

In a possible design, before the sending, by the control plane networkelement, a first indication message including the first time period tothe user plane network element that has started a second timer, themethod further includes: sending, by the control plane network element,a second indication message to the user plane network element, where thesecond indication message is used to instruct the user plane networkelement to configure the timed duration of the second timer to thesecond time period, so that the user plane network element buffers thedownlink data packet within the timed duration of the second timer.Therefore, the control plane network element delivers the secondindication message to the user plane network element, so that the secondtimer does not need to be configured in the user plane network elementmanually, facilitating configuration of the second timer in the userplane network element and facilitating adjustment on the timed durationof the second timer.

In a possible design, after the starting, by the control plane networkelement, a first timer based on the delay instruction, the methodfurther includes: if the control plane network element has received,within the first time period, the routing information of the basestation sent by the mobility management network element, stopping, bythe control plane network element, timing of the first timer, andsending the routing information of the base station to the user planenetwork element; or if the control plane network element has notreceived, within the first time period, the routing information of thebase station sent by the mobility management network element, sending,by the control plane network element, a third indication message to theuser plane network element, where the third indication message is usedto instruct the user plane network element to stop timing of the secondtimer and discard the buffered downlink data packet and the bufferedsubsequently received downlink data packet. Therefore, the first timerand the second timer are set, so that the time by which DDN messagesending is delayed can be controlled appropriately by using the timermechanism, and the relatively great impact caused to the serviceexperience of the user because the user service cannot be responded todue to the long time delay can be avoided.

In a possible design, the event report message further includes thedownlink data packet, or the event report message further includes thedownlink data packet and identifier information, and the identifierinformation is used to determine that the downlink data packet is sentto the UE; and the determining, by the control plane network element,that the UE is registered in the mobility management network elementincludes: determining, by the control plane network element based on adestination address of the downlink data packet and locally storedcontext information of the UE, that the UE is registered in the mobilitymanagement network element, where the destination address is an(Internet Protocol) IP address of the UE; or determining, by the controlplane network element based on the identifier information and locallystored context information of the UE, that the UE is registered in themobility management network element. Therefore, the control planenetwork element can rapidly and accurately determine, based on thedownlink data packet or the identifier information, the corresponding UEfor which DDN message sending needs to be delayed, and determine themobility management network element of the UE. Further, compared with UErecognition based on the downlink data packet, recognition based on theidentifier information enables the control plane network element torapidly recognize the UE with no need to parse the downlink data packet.

In a possible design, after the receiving, by the control plane networkelement, an event report message sent by a user plane network element,the method further includes: buffering, by the control plane networkelement, the downlink data packet. Therefore, a loss of the downlinkdata packet of the UE can be avoided.

In a possible design, the delay instruction includes a delay parameter,and after the determining, by the control plane network element, thatthe UE is registered in the mobility management network element, themethod further includes: starting, by the control plane network element,a third timer based on the delay instruction, and configuring timedduration of the third timer to the first time period based on the delayparameter; and sending, by the control plane network element, a fourthindication message including the first time period to the user planenetwork element, where the fourth indication message is used by the userplane network element to start a fourth timer and configure timedduration of the fourth timer to the first time period, so that the userplane network element buffers a subsequently received downlink datapacket within the timed duration of the fourth timer; or sending, by thecontrol plane network element, a fourth indication message including adiscarding instruction to the user plane network element, where thefourth indication message is used to instruct the user plane networkelement to discard a subsequently received downlink data packet.Therefore, the third timer and the fourth timer are set, in other words,the timer mechanism is set, so that effective utilization of a networkresource can be ensured, and long-time occupation of storage resourcesof the control plane network element and the user plane network elementcaused because the downlink data packet is buffered for a long time isavoided.

In a possible design, after the starting, by the control plane networkelement, the third timer based on the delay instruction, the methodfurther includes: if the control plane network element has received,within the first time period, the routing information of the basestation sent by the mobility management network element, stopping, bythe control plane network element, timing of the third timer, andsending the routing information of the base station and the buffereddownlink data packet to the user plane network element; or if thecontrol plane network element has not received, within the first timeperiod, the routing information of the base station sent by the mobilitymanagement network element, discarding, by the control plane networkelement, the buffered downlink data packet, and sending a fifthindication message to the user plane network element, where the fifthindication message is used to instruct the user plane network element tostop timing of the fourth timer and discard the buffered subsequentlyreceived downlink data packet. Therefore, the time by which DDN messagesending is delayed can be controlled appropriately by using the timermechanism, and the relatively great impact caused to the serviceexperience of the user because the user service cannot be responded todue to the long time delay can be avoided.

According to another aspect, an embodiment of the present inventionprovides a downlink data notification (DDN) message sending method. Themethod includes: receiving, by a user plane network element, a downlinkdata packet sent to UE, where the downlink data packet matches nobearer. The method also includes sending, by the user plane networkelement, an event report message to a control plane network element,where the event report message includes a reported event, and thereported event is used to notify the control plane network element thatthe downlink data packet matches no bearer, so that the control planenetwork element delays sending a DDN message to a mobility managementnetwork element.

Therefore, the event report message is reported, so that processingcomplexity of the user plane network element can be lowered, and thecontrol plane network element can delay sending a DDN message to themobility management network element, reducing DDN message sending, andreducing signaling load of the mobility management network element.

In a possible design, the event report message further includesidentifier information, and the identifier information is used todetermine that the downlink data packet is sent to the UE, so that thecontrol plane network element determines, based on the identifierinformation and locally stored context information of the UE, that theUE is registered in the mobility management network element. Therefore,the control plane network element can rapidly and accurately determine,based on the identifier information, the UE corresponding to thereported event and the mobility management network element in which theUE is registered.

In a possible design, after the receiving, by a user plane networkelement, a downlink data packet sent to UE, the method further includes:starting, by the user plane network element, a timer, where timedduration of the timer is a second time period; and buffering thedownlink data packet within the timed duration of the timer. Therefore,when it is ensured that the downlink data packet is not lost, comparedwith that the downlink data packet is sent to the control plane networkelement for buffering, when the user plane network element buffers thedownlink data packet, a network transmission amount can be reduced.

In a possible design, before the receiving, by a user plane networkelement, a downlink data packet sent to UE, the method further includes:receiving, by the user plane network element, a second indicationmessage sent by the control plane network element, where the secondindication message is used to instruct the user plane network element toconfigure the timed duration of the timer to the second time period.Therefore, the timer does not need to be configured in the user planenetwork element manually, facilitating timing setting performed by thecontrol plane network element for the user plane network element.

In a possible design, after the sending, by the user plane networkelement, an event report message to a control plane network element, themethod further includes: receiving, by the user plane network element, afirst indication message sent by the control plane network element,where the first indication message includes a first time period;restarting, by the user plane network element, the timer and configuringthe timed duration of the timer to the first time period based on thefirst indication message; or configuring, by the user plane networkelement, the timed duration of the timer to a sum of the second timeperiod and the first time period based on the first indication message;and buffering, by the user plane network element, a subsequentlyreceived downlink data packet based on the timed duration of the timer.Therefore, a timer mechanism is set, so that the user plane networkelement can buffer the downlink data packet based on duration setting ofthe timer, ensuring that the downlink data packet is not lost, andavoiding relatively great impact caused to service experience of a userbecause a user service cannot be responded to due to long-timebuffering. Further, a method for reusing the timer in the user planenetwork element is further provided, in other words, the timed durationof the timer is extended, so that processing complexity of restarting,by the user plane network element, the timer can be lowered.

In a possible design, the method further includes: if the user planenetwork element has received, within the timed duration of the timer,routing information of a base station sent by the control plane networkelement, stopping, by the user plane network element, timing of thetimer, and sending the buffered downlink data packet and the bufferedsubsequently received downlink data packet to the UE, where the routinginformation of the base station is used to identify a bearer.Alternatively, if the user plane network element has received, withinthe timed duration of the timer, a third indication message sent by thecontrol plane network element, stopping, by the user plane networkelement, timing of the timer and discarding the buffered downlink datapacket and the buffered subsequently received downlink data packet basedon the third indication message. Therefore, a time for which the userplane network element buffers the downlink data packet can be controlledappropriately by using the timer mechanism, and the relatively greatimpact caused to the service experience of the user because the userservice cannot be responded to due to long-time timing setting can beavoided.

In a possible design, the event report message further includes thedownlink data packet, or the event report message further includes thedownlink data packet and identifier information, and the identifierinformation is used to determine that the downlink data packet is sentto the UE, so that the control plane network element determines, basedon a destination address of the downlink data packet and locally storedcontext information of the UE, that the UE is registered in the mobilitymanagement network element, where the destination address is an(Internet Protocol) IP address of the UE; or so that the control planenetwork element determines, based on the identifier information andlocally stored context information of the UE, that the UE is registeredin the mobility management network element. Therefore, the control planenetwork element can rapidly and accurately determine the UEcorresponding to the reported event. Further, when the identifierinformation is carried, the control plane network element can rapidlyrecognize the UE, and does not need to parse the downlink data packet.

In a possible design, after the sending, by the user plane networkelement, an event report message to a control plane network element, themethod further includes: receiving, by the user plane network element, afourth indication message sent by the control plane network element,where the fourth indication message includes a first time period;starting, by the user plane network element, a timer and configuringtimed duration of the timer to the first time period based on the fourthindication message; and buffering, by the user plane network element, asubsequently received downlink data packet within the timed duration ofthe timer; or receiving, by the user plane network element, a fourthindication message sent by the control plane network element, where thefourth indication message includes a discarding instruction; anddiscarding, by the user plane network element, a subsequently receiveddownlink data packet based on the fourth indication message. Therefore,the downlink data packet is buffered by using the timer mechanism, sothat effective utilization of a network resource can be ensured, andlong-time occupation of a storage resource of the user plane networkelement caused because the user plane network element buffers data for along time can be avoided.

In a possible design, the method further includes: if the user planenetwork element has received, within the timed duration of the timer,routing information of a base station and the buffered downlink datapacket that are sent by the control plane network element, stopping, bythe user plane network element, timing of the timer, and sending thebuffered downlink data packet and the buffered subsequently receiveddownlink data packet to the UE, where the routing information of thebase station is used to identify a bearer; or if the user plane networkelement has received, within the timed duration of the timer, a fifthindication message sent by the control plane network element, stopping,by the user plane network element, timing of the timer, and discardingthe buffered subsequently received downlink data packet. Therefore, atime for which the user plane network element buffers the downlink datapacket can be controlled appropriately by using the timer mechanism, andthe relatively great impact caused to the service experience of the userbecause the user service cannot be responded to due to long-time databuffering can be avoided.

According to still another aspect, an embodiment of the presentinvention provides a control plane network element. The control planenetwork element has a function of implementing behaviors of the controlplane network element in the foregoing method designs. The function maybe implemented by using hardware, or may be implemented by hardwareexecuting corresponding software. The hardware or software includes oneor more modules corresponding to the function.

In a possible design, a structure of the control plane network elementincludes a processor and a network interface. The processor isconfigured to support the control plane network element in performingcorresponding functions in the method, and the network interface isconfigured to support communication between the control plane networkelement and a user plane network element and communication between thecontrol plane network element and a mobility management network element.For example, the processor is configured to receive, by using thenetwork interface, a delay instruction sent by the mobility managementnetwork element, where the delay instruction is used to instruct thecontrol plane network element to delay sending a DDN message. Theprocessor is further configured to receive, by using the networkinterface, an event report message sent by the user plane networkelement, where the event report message includes a reported event, andthe reported event is used to notify the control plane network elementthat a downlink data packet sent to UE matches no bearer. The processoris further configured to determine that the UE is registered in themobility management network element. The processor is further configuredto: if the control plane network element has not received, within afirst time period, routing information of a base station sent by themobility management network element, send the DDN message to themobility management network element by using the network interface whenthe first time period expires, where the routing information of the basestation is used to identify a bearer. The control plane network elementmay further include a memory. The memory is configured to be coupled tothe processor and stores a program instruction and data that arerequired by the control plane network element.

According to still another aspect, an embodiment of the presentinvention provides a user plane network element. The user plane networkelement has a function of implementing behaviors of the user planenetwork element in the foregoing method designs. The function may beimplemented by using hardware, or may be implemented by hardwareexecuting corresponding software. The hardware or software includes oneor more modules corresponding to the function.

In a possible design, a structure of the user plane network elementincludes a processor and a network interface. The processor isconfigured to support the user plane network element in performingcorresponding functions in the foregoing method, and the networkinterface is configured to support communication between the user planenetwork element and a control plane network element. For example, theprocessor is configured to receive, by using the network interface, adownlink data packet sent to UE, where the downlink data packet matchesno bearer. The processor is further configured to send an event reportmessage to the control plane network element by using the networkinterface, where the event report message includes a reported event, andthe reported event is used to notify the control plane network elementthat the downlink data packet matches no bearer, so that the controlplane network element delays sending a DDN message to a mobilitymanagement network element. The user plane network element may furtherinclude a memory. The memory is configured to be coupled to theprocessor and stores a program instruction and data that are required bythe user plane network element.

According to still another aspect, an embodiment of the presentinvention provides a communications system. The system includes thecontrol plane network element and the user plane network element in theforegoing aspects.

According to yet another aspect, an embodiment of the present inventionprovides a computer storage medium, configured to store a computersoftware instruction used by the control plane network element, wherethe computer software instruction includes a program designed to performthe foregoing aspect.

According to yet another aspect, an embodiment of the present inventionprovides a computer storage medium, configured to store a computersoftware instruction used by the user plane network element, where thecomputer software instruction includes a program designed to perform theforegoing aspect.

Compared with the prior art, in the solutions provided in the presentinvention, DDN message sending can be completed in a case of C/Useparation, lowering processing complexity of the user plane networkelement. Further, DDN message sending can be reduced, reducing signalingload of the mobility management network element.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention or in the prior art more clearly, the following brieflydescribes the accompanying drawings required for describing theembodiments or the prior art. Apparently, the accompanying drawings inthe following description show merely some embodiments of the presentinvention, and a person of ordinary skill in the art may still deriveother drawings from these accompanying drawings without creativeefforts.

FIG. 1 is a schematic diagram of an EPS network architecture in acurrent system;

FIG. 2 is a schematic diagram of an EPS network architecture accordingto an embodiment of the present invention;

FIG. 3 is a schematic diagram of another EPS network architectureaccording to an embodiment of the present invention;

FIG. 4 is a schematic flowchart of a DDN message sending methodaccording to an embodiment of the present invention;

FIG. 5 is a schematic communication diagram of a service requestprocedure of UE according to an embodiment of the present invention;

FIG. 6 is a schematic flowchart of another DDN message sending methodaccording to an embodiment of the present invention;

FIG. 7A and FIG. 7B are a schematic flowchart of still another DDNmessage sending method according to an embodiment of the presentinvention;

FIG. 8 is a schematic structural diagram of a control plane networkelement according to an embodiment of the present invention; and

FIG. 9 is a schematic structural diagram of a user plane network elementaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following describes the technical solutions in the embodiments ofthe present invention with reference to the accompanying drawings in theembodiments of the present invention. Apparently, the describedembodiments are merely some but not all of the embodiments of thepresent invention. All other embodiments obtained by a person ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

A network architecture and a service scenario that are described in theembodiments of the present invention are intended to describe thetechnical solutions of the embodiments of the present invention moreclearly, but do not constitute a limitation to the technical solutionsprovided in the embodiments of the present invention. A person ofordinary skill in the art may learn that as the network architectureevolves and a new service scenario emerges, the technical solutionsprovided in the embodiments of the present invention are also applicableto similar technical problems.

The technical solutions of the embodiments of the present invention maybe applied to a network architecture in which a control plane functionand a user plane function of gateway functions are decoupled, in otherwords, are applied to a network architecture in which a control planefunction and a user plane function separately form two independentnetwork entities.

A transmission delay of user plane data may be reduced by movingdownwards a user plane gateway and deploying a distributed gateway. Aconventional gateway is deployed at a very high location. Moving thegateway downwards refers to: moving a deployment location of the gatewaydownwards, for example, the gateway is deployed at a location relativelyclose to UE. For example, the gateway may be deployed together with anevolved NodeB (eNB) in a distributed manner. In this way, the UE canrapidly access a packet data network (PDN) by using the gateway that ismoved downwards, improving user experience.

FIG. 2 is a schematic diagram of an EPS network architecture accordingto an embodiment of the present invention. The EPS network architectureincludes a DGW and a CGW. In FIG. 2, an interface between the CGW andthe DGW is an S18 interface. The S18 interface may use an interfaceprotocol between an SGW and a PGW in an existing EPS networkarchitecture, for example, the General Packet Radio Service (GPRS)Tunneling Protocol (“GPRS Tunneling Protocol” or “GTP”), or may useanother interface protocol or a newly defined protocol. This is notlimited in this embodiment of the present invention. In the networkarchitecture, other than the introduced CGW, DGW, and S18 interfacebetween the CGW and the DGW, another network element and interface mayuse a network element and an interface in the existing EPS networkarchitecture. In the network architecture shown in FIG. 2, atransmission path of control plane signaling in an uplink directionstarts from UE, sequentially passes through an evolved universalterrestrial radio access network (E-UTRAN), an MME, the CGW, and apolicy and charging rules function (PCRF) entity, and finally arrives ata server. A transmission path of user plane data in an uplink directionstarts from the UE, sequentially passes through the E-UTRAN and the DGW,and finally arrives at the server.

FIG. 3 is a schematic diagram of another EPS network architectureaccording to an embodiment of the present invention. The EPS networkstructure includes control plane gateways: an SGW-C and a PGW-C, anduser plane gateways: an SGW-U and a PGW-U. In FIG. 3, an interfacebetween the SGW-C and the SGW-U is an S18 interface, and an interfacebetween the PGW-C and the PGW-U is an S19 interface. The S18 interfacemay use an interface protocol between an SGW and a PGW in an existingEPS network architecture, for example, GTP, or may use another interfaceprotocol or a newly defined protocol. This is not limited in thisembodiment of the present invention. In the network architecture, otherthan the introduced SGW-C, SGW-U, and S18 interface between the SGW-Cand the SGW-U, another network element and interface may use a networkelement and an interface in the existing EPS network architecture. Inthe network architecture shown in FIG. 3, a transmission path of controlplane signaling in an uplink direction starts from UE, sequentiallypasses through an E-UTRAN, an MME, the SGW-C, the PGW-C, and a PCRFentity, and finally arrives at a server. A transmission path of userplane data in an uplink direction starts from the UE, sequentiallypasses through the E-UTRAN, the SGW-U, and the PGW-U, and finallyarrives at the server.

The technical solutions of the embodiments of the present invention maybe applicable to a scenario of an access manner defined by the 3rdGeneration Partnership Project (3GPP), or may be applicable to ascenario of a non-3GPP access manner. The embodiments of the presentinvention are described by using an EPS network architecture in ascenario of a 3GPP access manner as an example.

The following further describes in detail the embodiments of the presentinvention based on the foregoing common aspects of the presentinvention.

The embodiments of the present invention provide a DDN message sendingmethod, and a control plane network element and a user plane networkelement that are based on the method. The control plane network elementmay be a control plane gateway or another control plane managemententity, and the user plane network element may be a user plane gatewayor another user plane management entity. The control plane networkelement receives a delay instruction sent by a mobility managementnetwork element, where the delay instruction is used to instruct thecontrol plane network element to delay sending a DDN message. The userplane network element receives a downlink data packet sent to UE, wherethe downlink data packet matches no bearer. The user plane networkelement sends an event report message to the control plane networkelement, where the event report message includes a reported event, andthe reported event is used to notify the control plane network elementthat the downlink data packet matches no bearer, so that the controlplane network element delays sending the DDN message to the mobilitymanagement network element. Correspondingly, the control plane networkelement receives the event report message sent by the user plane networkelement. After the control plane network element determines that the UEis registered in the mobility management network element, if the controlplane network element has not received, within a first time period,routing information of a base station sent by the mobility managementnetwork element, the control plane network element sends the DDN messageto the mobility management network element when the first time periodexpires, and the routing information of the base station is used toidentify a bearer.

In the technical solutions of the embodiments of the present invention,if the user plane network element receives a downlink data packet ofidle-state UE, the user plane network element sends an event reportmessage to the control plane network element, the control plane networkelement determines, based on a DDN message sending delay instruction ofthe mobility management network element and the event report message,whether to delay sending a DDN message to the mobility managementnetwork element, and if DDN message sending needs to be delayed, thecontrol plane network element delays sending the DDN message.

The following describes, with reference to FIG. 4, the solutionsprovided in the embodiments of the present invention.

FIG. 4 is a schematic flowchart of a DDN message sending methodaccording to an embodiment of the present invention. As shown in FIG. 4,the method includes the following steps.

401. A control plane network element receives a delay instruction sentby a mobility management network element, where the delay instruction isused to instruct the control plane network element to delay sending aDDN message.

In an example, the delay instruction is a downlink packet delaynotification request. The control plane network element receives abearer modification request message sent by the mobility managementnetwork element, and the bearer modification request message carries thedownlink packet delay notification request. Optionally, the downlinkpacket delay notification request further carries a delay parameter, andthe delay parameter represents a time length.

402. A user plane network element receives a downlink data packet sentto UE, where the downlink data packet matches no bearer.

In an example, the user plane network element uses an idle-state UE databuffering mechanism. Using the user plane network element as an example,the idle-state UE data buffering mechanism means that because a downlinkdata packet sent to idle-state UE matches no bearer, the downlink datapacket cannot be sent to the UE, and when the user plane network elementreceives the downlink data packet sent to the idle-state UE, the userplane network element buffers the downlink data packet. Therefore, whenthe user plane network element buffers the downlink data packet, adownlink data packet loss can be avoided. For example, before receivingthe downlink data packet, the user plane network element locallyconfigures a second timer, and timed duration of the second timer is asecond time period. Alternatively, before the user plane network elementreceives the downlink data packet, the control plane network elementsends a second indication message to the user plane network element, andthe second indication message is used to instruct the user plane networkelement to configure timed duration of a second timer to a second timeperiod, and correspondingly, the user plane network element receives thesecond indication message sent by the control plane network element, andconfigures the timed duration of the second timer to the second timeperiod based on the second indication message. When receiving thedownlink data packet sent to the idle-state UE, the user plane networkelement starts the local second timer, and starts to buffer the downlinkdata packet within the timed duration of the timer. Therefore, thesecond timer is set, so that the user plane network element can bufferthe downlink data packet based on duration setting of the second timer,ensuring that the downlink data packet is not lost, and avoidingrelatively great impact caused to service experience of a user because auser service cannot be responded to due to long-time buffering.

In an example, the user plane network element does not use theidle-state UE data buffering mechanism, but the control plane networkelement uses the idle-state UE data buffering mechanism. When receivingthe downlink data packet, the user plane network element does not bufferthe downlink data packet. Further, compared with that the downlink datapacket is sent to the control plane network element for buffering, whenthe user plane network element buffers the downlink data packet, anetwork transmission amount can be reduced.

403. The user plane network element sends an event report message to thecontrol plane network element, where the event report message includes areported event, and the reported event is used to notify the controlplane network element that the downlink data packet matches no bearer,so that the control plane network element delays sending the DDN messageto the mobility management network element.

When the downlink data packet of the UE received by the user planenetwork element matches no bearer, the user plane network element cannotsend the downlink data packet to the UE, and the user plane networkelement sends the reported event indicating that the downlink datapacket matches no bearer to the control plane network element.

In an example, the event report message may further carry identifierinformation, and the identifier information is used to determine thatthe downlink data packet is sent to the UE; or the event report messagemay further carry the downlink data packet, or the downlink data packetand identifier information. For example, when the user plane networkelement uses the idle-state UE data buffering mechanism, in addition tothe reported event, the event report message further carries theidentifier information. When the control plane network element uses theidle-state UE data buffering mechanism, because the user plane networkelement does not buffer the downlink data packet, in addition to thereported event, the event report message further carries the downlinkdata packet, or further carries the downlink data packet and theidentifier information. Therefore, the control plane network element canrapidly and accurately determine, based on the identifier information orthe downlink data packet, the UE corresponding to the reported event andthe mobility management network element in which the UE is registered.The control plane network element determines the UE based on theidentifier information, and may not need to parse the downlink datapacket, lowering processing complexity of the control plane networkelement.

404. The control plane network element receives the event report messagesent by the user plane network element.

In an example, when the event report message carries the downlink datapacket, the control plane network element buffers the downlink datapacket after receiving the event report message, ensuring that thedownlink data packet is not lost.

405. The control plane network element determines whether the UE isregistered in the mobility management network element.

In an example, the control plane network element determines, based oncontent carried in the event report message and locally stored contextinformation of the UE, whether the UE is registered in the mobilitymanagement network element. For example, when the event report messagecarries the reported event and the identifier information, the controlplane network element determines, based on the identifier informationand the locally stored context information of the UE, that the UE isregistered in the mobility management network element. When the eventreport message carries the reported event and the downlink data packet,the control plane network element determines, based on a destinationaddress of the downlink data packet and the locally stored contextinformation of the UE, that the UE is registered in the mobilitymanagement network element, and the destination address is an InternetProtocol (IP) address of the UE. It may be understood that when theevent report message further carries the identifier information inaddition to the reported event and the downlink data packet, the controlplane network element may also determine, based on the identifierinformation and the locally stored context information of the UE, thatthe UE is registered in the mobility management network element.Therefore, the control plane network element can rapidly and accuratelydetermine, based on the identifier information or the downlink datapacket, the mobility management network element in which the UEcorresponding to the reported event is registered. The control planenetwork element determines the mobility management network elementcorresponding to the UE based on the identifier information, and may notneed to parse the downlink data packet, lowering processing complexityof the control plane network element.

In an example, the control plane network element first determines, basedon the content carried in the event report message and the locallystored context information of the UE, a mobility management networkelement in which the UE is registered, and then determines whether themobility management network element in which the UE is registeredmatches the mobility management network element sending the delayinstruction to the control plane network element, and if they match, thecontrol plane network element determines that the UE is registered inthe mobility management network element; or if they do not match, thecontrol plane network element determines that the UE is not registeredin the mobility management network element.

In an example, when the user plane network element uses the idle-stateUE data buffering mechanism, if the control plane network elementdetermines that the UE is registered in the mobility management networkelement, the control plane network element starts a first timer based onthe delay instruction, and configures timed duration of the first timerto a first time period based on the delay parameter. For example, thefirst time period may be a time period whose length is one delayparameter, or may be a time period whose length is a sum of a pluralityof delay parameters. The control plane network element sends a firstindication message including the first time period to the user planenetwork element, and the first indication message is used by the userplane network element to restart the second timer and configure thetimed duration of the second timer to the first time period, or is usedby the user plane network element to configure the timed duration of thesecond timer to a sum of the second time period and the first timeperiod, so that the user plane network element buffers a subsequentlyreceived downlink data packet. Correspondingly, the user plane networkelement receives the first indication message including the first timeperiod and sent by the control plane network element, and restarts thesecond timer and configures the timed duration of the second timer tothe first time period based on the first indication message, or the userplane network element configures the timed duration of the second timerto the sum of the second time period and the first time period based onthe first indication message. Subsequently, the user plane networkelement buffers the subsequently received downlink data packet based onthe timed duration of the second timer. Therefore, the first timer isset, so that a delaying time by which the control plane network elementdelays sending a DDN message can be controlled appropriately; the secondtimer is set, so that relatively great impact caused to serviceexperience of a user because a user service cannot be responded to dueto long-time data buffering of the user plane network element isavoided. Further, a method for instructing the user plane networkelement to reuse the second timer is used, in other words, the timedduration of the second timer is directly extended, so that processingcomplexity of restarting, by the user plane network element, a timer canbe lowered.

In an example, when the control plane network element uses theidle-state UE data buffering mechanism, if the control plane networkelement determines that the UE is registered in the mobility managementnetwork element, the control plane network element starts a third timerbased on the delay instruction, and configures timed duration of thethird timer to the first time period based on the delay parameter. Thecontrol plane network element sends a fourth indication messageincluding the first time period to the user plane network element, andthe fourth indication message is used by the user plane network elementto start a fourth timer and configure timed duration of the fourth timerto the first time period, so that the user plane network element buffersthe subsequently received downlink data packet within the timed durationof the fourth timer. Alternatively, the control plane network elementsends a fourth indication message including a discarding instruction tothe user plane network element, and the fourth indication message isused to instruct the user plane network element to discard thesubsequently received downlink data packet. Correspondingly, the userplane network element receives the fourth indication message includingthe first time period and sent by the control plane network element, andthe user plane network element starts the fourth timer and configuresthe timed duration of the fourth timer to the first time period based onthe fourth indication message, and buffers the subsequently receiveddownlink data packet within the timed duration of the fourth timer.Alternatively, the user plane network element receives the fourthindication message including the discarding instruction and sent by thecontrol plane network element, and the user plane network elementdiscards the subsequently received downlink data packet based on thefourth indication message. By using the timer mechanism of the controlplane network element and the user plane network element, the delayingtime by which the control plane network element delays sending the DDNmessage can be controlled appropriately, so that relatively great impactcaused to service experience of a user because a user service cannot beresponded to due to long-time data buffering of the control planenetwork element is avoided. Further, a method for instructing the userplane network element to reuse the fourth timer is used, in other words,the timed duration of the fourth timer is directly extended, so that theprocessing complexity of restarting, by the user plane network element,a timer can be lowered. Compared with that the control plane networkelement uses the idle-state UE data buffering mechanism, when the userplane network element uses the idle-state UE data buffering mechanism, anetwork transmission amount can be reduced, to be specific, the downlinkdata packet does not need to be sent to the control plane networkelement by using the user plane network element.

406. If the control plane network element has not received, within afirst time period, routing information of a base station sent by themobility management network element, the control plane network elementsends the DDN message to the mobility management network element whenthe first time period expires, where the routing information of the basestation is used to identify a bearer. For example, the routinginformation of the base station may include a tunnel endpoint identifier(TEID) and address information of the base station.

In an example, when the user plane network element uses the idle-stateUE data buffering mechanism, if the control plane network element hasreceived, within the first time period, the routing information of thebase station sent by the mobility management network element, thecontrol plane network element stops timing of the first timer, and sendsthe routing information of the base station to the user plane networkelement; or if the control plane network element has not received,within the first time period, the routing information of the basestation sent by the mobility management network element, the controlplane network element sends a third indication message to the user planenetwork element, and the third indication message is used to instructthe user plane network element to stop timing of the second timer anddiscard the buffered downlink data packet and the buffered subsequentlyreceived downlink data packet. It should be noted that when the firsttimer expires and the control plane network element has not received therouting information of the base station sent by the mobility managementnetwork element, the control plane network element may further restartthe first timer, where the timed duration is the first time period or anew specified time period, and resend the first indication message tothe user plane network element, where the first indication message isused by the user plane network element to restart the second timer andconfigure the timed duration of the second timer to the first timeperiod or the new time period, or is used by the user plane networkelement to configure the timed duration of the second timer to the sumof the second time period and the first time period or a sum of thesecond time period and the new time period, so that the user planenetwork element buffers the received downlink data packet. When thecontrol plane network element has not received, within the first timeperiod or the new time period after restarting the first timer, therouting information of the base station sent by the mobility managementnetwork element, the control plane network element sends the thirdindication message to the user plane network element.

In an example, when the control plane network element uses theidle-state UE data buffering mechanism, if the control plane networkelement has received, within the first time period, the routinginformation of the base station sent by the mobility management networkelement, the control plane network element stops timing of the thirdtimer, and sends the routing information of the base station and thedownlink data packet buffered by the control plane network element tothe user plane network element; or if the control plane network elementhas not received, within the first time period, the routing informationof the base station sent by the mobility management network element, thecontrol plane network element discards the buffered downlink datapacket, and sends a fifth indication message to the user plane networkelement, and the fifth indication message is used to instruct the userplane network element to stop timing of the fourth timer and discard thebuffered subsequently received downlink data packet. It should be notedthat when the third timer expires and the control plane network elementhas not received the routing information of the base station sent by themobility management network element, the control plane network elementmay further restart the third timer, where the timed duration is thefirst time period or a new specified time period, and resend the fourthindication message including the first time period or the new timeperiod to the user plane network element, where the fourth indicationmessage is used by the user plane network element to restart the fourthtimer and configure the timed duration of the fourth timer to the firsttime period or the new time period, or is used by the user plane networkelement to configure the timed duration of the fourth timer to a sum ofthe second time period and the first time period or a sum of the secondtime period and the new time period, so that the user plane networkelement buffers the subsequently received downlink data packet. When thecontrol plane network element has not received, within the first timeperiod or the new time period after restarting the first timer, therouting information of the base station sent by the mobility managementnetwork element, the control plane network element sends the fifthindication message to the user plane network element.

In an example, when the user plane network element uses the idle-stateUE data buffering mechanism, if the user plane network element hasreceived, within the timed duration of the second timer, the routinginformation of the base station sent by the control plane networkelement, the user plane network element stops timing of the secondtimer, and sends the buffered downlink data packet and the bufferedsubsequently received downlink data packet to the UE; or if the userplane network element has received, within the timed duration of thesecond timer, the third indication message sent by the control planenetwork element, the user plane network element stops timing of thesecond timer and discards the buffered downlink data packet and thebuffered subsequently received downlink data packet based on the thirdindication message.

In an example, when the control plane network element uses theidle-state UE data buffering mechanism, if the user plane networkelement has received, within the timed duration of the second timer, therouting information of the base station and the buffered downlink datapacket that are sent by the control plane network element, the userplane network element stops timing of the fourth timer, and sends thebuffered downlink data packet and the buffered subsequently receiveddownlink data packet to the UE; or if the user plane network element hasreceived, within the timed duration of the second timer, the fifthindication message sent by the control plane network element, the userplane network element stops timing of the fourth timer, and discards thebuffered subsequently received downlink data packet.

Therefore, by using the timer mechanism, the delaying time by which thecontrol plane network element delays sending the DDN message can becontrolled appropriately, and the relatively great impact caused to theservice experience of the user because the user service cannot beresponded to due to the long-time data buffering of the control planenetwork element is avoided. Further, effective utilization of a networkresource can be ensured, and long-time occupation of storage resourcesof the control plane network element and the user plane network elementcaused because the downlink data packet is buffered for a long time isavoided.

In this embodiment of the present invention, if the control planenetwork element determines that the UE is registered in the mobilitymanagement network element sending the delay instruction, the controlplane network element does not directly send the DDN message to themobility management network element, instead, the control plane networkelement first determines whether the control plane network element hasreceived, within the first time period, the routing information of thebase station sent by the mobility management network element, and if thecontrol plane network element has received the routing information, thecontrol plane network element does not need to send the DDN message tothe mobility management network element, so that unnecessary DDN messagesending can be reduced, and signaling load of the mobility managementnetwork element can be reduced. If the control plane network element hasnot received, within the first time period, the routing information ofthe base station sent by the mobility management network element, thecontrol plane network element sends the DDN message to the mobilitymanagement network element only when the first time period expires.Relative to processing complexity of a user plane network element in theprior art in which the user plane network element is unaware of amobility management network element in which UE is registered, in thisembodiment of the present invention, the control plane network elementcan determine, based on the event report message reported by the userplane network element, the mobility management network element in whichthe UE is registered, to complete DDN message sending, so that theprocessing complexity of the user plane network element is lowered.

The solution of this embodiment of the present invention may be appliedto the network architecture shown in FIG. 2 or FIG. 3. When the solutionis applied to the network architecture shown in FIG. 2, the controlplane network element may be a CGW, and the user plane network elementmay be a DGW. When the solution is applied to the network architectureshown in FIG. 3, the control plane network element may be an SGW-C, andthe user plane network element may be an SGW-U, or the control planenetwork element may be a PGW-C, and the user plane network element maybe a PGW-U.

The following further describes the embodiments of the present inventionbased on the network architecture shown in FIG. 2 with reference to moreaccompanying drawings by using an example in which a control planenetwork element is a CGW, a user plane network element is a DGW, and amobility management network element is an MME.

FIG. 5 is a schematic communication diagram of a service requestprocedure according to an embodiment of the present invention.

When UE is in an idle state, if the UE needs to send an uplink datapacket or needs to receive a downlink data packet, a service requestprocedure of the UE is triggered because the idle-state UE does not havea user plane S1 path or radio bearer (RB), in other words, does not havean S1-U or a Uu user plane transmission bearer in FIG. 2 or FIG. 3. AnMME may send a delay instruction to a CGW in the service requestprocedure. The service request procedure is shown in FIG. 5. In step508, the MME sends a bearer modification request message to the CGW,where the bearer modification request message carries a delayinstruction. The delay instruction may be a downlink packet delaynotification request. Further, the downlink packet delay notificationrequest may include a delay parameter.

FIG. 6 is a schematic flowchart of another DDN message sending methodaccording to an embodiment of the present invention. In the method shownin FIG. 6, a DGW uses an idle-state UE data buffering mechanism. Asshown in FIG. 6, the method includes the following steps.

601. A CGW receives a delay instruction sent by an MME, where the delayinstruction is used to instruct the CGW to delay sending a DDN messageto the MME.

In an example, the delay instruction is the downlink packet delaynotification request carried in the bearer modification request message.Further, the downlink packet delay notification request includes thedelay parameter.

602. The DGW receives a downlink data packet sent to idle-state UE.

If the DGW matches the received downlink data packet of the UE to nobearer, for example, the DGW has not received routing information of aneNB, the DGW may determine that the UE is currently in an idle state.

603. The DGW starts a second timer, where timed duration is a secondtime period; and buffers the downlink data packet within the timedduration.

The DGW uses the idle-state UE data buffering mechanism. The DGW buffersthe received downlink data packet and a subsequently received downlinkdata packet within the timed duration after starting the second timer. Asame service of same UE corresponds to a same bearer, to be specific, abase station corresponding to the same service of the same UE has a sameTEID and same address information. Therefore, this embodiment of thepresent invention is described by using a downlink data packetcorresponding to a same service of same UE.

In an example, the DGW locally configures the second timer, and thetimed duration is the second time period. In this case, the DGW startsthe local second timer, and starts to buffer the received downlink datapacket and the subsequently received downlink data packet. In anotherexample, the second timer of the DGW is configured by the DGW based onan instruction of the CGW. For example, the CGW may send a secondindication message to the DGW in advance by using another message of anS18 interface, and the second indication message is used to indicatethat the timed duration of the second timer is the second time period.When the DGW matches the downlink data packet to no bearer, the DGWstarts the second timer, and starts to buffer the received downlink datapacket. In this way, the second timer does not need to be configured inthe DGW manually, and adjustment on the timed duration of the secondtimer is facilitated.

If the DGW has received, before the second timer of the DGW expires, inother words, within the timed duration of the second timer, routinginformation of a base station sent by the CGW, the DGW stops timing ofthe second timer, establishes a corresponding bearer based on therouting information of the base station, and sends the buffered downlinkdata packet of the UE to the UE by using the corresponding bearer. Ifthe DGW has not received routing information of a base station after thesecond timer expires, the DGW may discard the buffered downlink datapacket of the UE, or the DGW may restart the second timer, and when aquantity of times of starting the second timer exceeds a specifiedthreshold, the DGW no longer starts the second timer, and in this case,discards the buffered downlink data packet of the UE.

604. The DGW sends an event report message to the CGW, where the eventreport message includes a reported event, and the reported event is usedto notify the CGW that the downlink data packet sent to the UE matchesno bearer.

In an example, the event report message further includes identifierinformation, and the identifier information is used to determine thatthe downlink data packet is sent to the UE. The identifier informationmay include at least one of a data flow identifier, a bearer identifier,a UE identifier, a PDN connection identifier, or a session identifier(for example, a session ID). For example, the data flow identifier maybe a traffic flow template (TFT), the bearer identifier may be an EPSbearer ID, and the UE identifier may be an international mobilesubscriber identity (IMSI) or a temporary mobile subscriber identity(TMSI). The event report message may carry one or more of theidentifiers. The identifiers may be directly presented in the eventreport message, or may be presented in another representation form, forexample, presented by using another new identifier formed by theidentifiers, for example, an object-based object identifier (object ID),including a session object identifier (session object ID), a bearerobject identifier (bearer object ID), or the like.

605. The CGW determines whether the UE is registered in the MME sendingthe delay instruction; and if determining that the UE is registered inthe MME, performs step 606; or if determining that the UE is notregistered in the MME, performs step 613.

After receiving the event report message sent by the DGW, the CGW maydetermine, based on the identifier information and context informationof the UE that is locally stored in the CGW, UE to which the event isspecific, and then determine, based on the context information of theUE, whether the UE is registered in the MME that previously instructsthe CGW to delay sending a DDN message, in other words, whether the UEis registered in the MME sending the delay instruction. For example, ifthe CGW has received the downlink packet delay notification request sentby the MME in which the UE is registered, the CGW determines that the UEis registered in the MME that has instructed the CGW to delay sending aDDN message. If the CGW determines that the UE is registered in an MMEthat does not instruct the CGW to delay sending a DDN message, in otherwords, the UE is not registered in the MME sending the delayinstruction, the CGW sends a DDN message to the MME, to trigger the MMEto page the UE, so that the UE initiates a service request procedure, asshown in FIG. 5.

In an example, an implementation in which the CGW determines, based onthe identifier information and the context information of the UE, the UEcorresponding to the reported event is: If the reported event sent bythe DGW is reported based on a flow granularity, in other words, the DGWadds only the data flow identifier (for example, the TFT) in the eventreport message, after receiving the identifier information, the CGWfirst needs to determine a bearer identifier corresponding to the TFT,further determines a PDN connection corresponding to the beareridentifier, and still further, determines UE to which the PDN connectionbelongs, so as to determine the UE corresponding to the reported event;or if the identifier information reported by the DGW includes the TFT,the EPS bearer ID, and the PDN connection identifier, the CGWdetermines, based on a combination of the identifiers, the UEcorresponding to the reported event; or if the DGW adds the UEidentifier in the identifier information, the CGW may directly determinethe UE corresponding to the reported event.

606. The CGW starts a first timer, where timed duration is a first timeperiod, and sends a first indication message including the first timeperiod to the DGW.

If the CGW determines that the UE is registered in the MME sending thedelay instruction, the CGW starts the local first timer, starts timingbased on the delay parameter in the delay instruction, in other words,configures the timed duration of the first timer to the first timeperiod based on the delay parameter, and sends the first indicationmessage including the first time period to the DGW, so that the DGWrestarts the second timer or extends the timed duration of the secondtimer, to continue to buffer the received downlink data packet and thesubsequently received downlink data packet.

607. The DGW restarts the second timer and configures the timed durationof the second timer to the first time period, or the DGW configures thetimed duration of the second timer to a sum of the second time periodand the first time period, and buffers a subsequently received downlinkdata packet within the timed duration of the second timer.

Based on the description of step 603, if the second timer in the DGW islocally configured by the DGW, the DGW does not know that the CGW hasstarted the first timer for buffering data. In this case, afterreceiving the first indication message including the first time periodand sent by the CGW, the DGW may stop the second timer that has beenstarted for timing in step 603, and restart timing based on the firsttime period, in other words, reset the duration of the second timer tothe first time period indicated by the CGW; or the DGW may add the firsttime period to the second time period of the second timer, to extend thetimed duration of the second timer.

If the second timer in the DGW is configured based on an instruction ofthe CGW, the CGW already knows that the DGW has started the second timerfor buffering data. In this case, the CGW may clearly instruct, by usingthe first indication message, the DGW to add the first time period tothe second time period of the second timer, to extend the timed durationof the second timer, or may clearly instruct the DGW to stop the timingsecond timer, restart the second timer, and set the duration to thefirst time period.

When the DGW restarts the second timer and configures the timed durationto the first time period, the DGW may keep timing of the second timersynchronized with timing of the first timer of the CGW. When the DGWextends the second time period by the first time period, rather thanrestarting the second timer, processing complexity of the second timercan be lowered.

608. The CGW determines whether routing information of a base stationhas been received within the first time period; and if the routinginformation has been received, performs step 609; or if the routinginformation has not been received, performs step 611.

In an example, if the CGW has not received the routing information ofthe base station within the first time period, in other words, has notreceived the routing information of the base station within the timedduration of the first timer, the CGW may further restart the firsttimer, and resend the first indication message to the DGW, to re-performstep 606, step 607, and step 608. When a quantity of times that the CGWstarts the first timer exceeds a predetermined threshold, and the CGWstill has not received the routing information of the base station, theCGW performs step 611. Timing of the first timer is set, so thatlong-time occupation of a storage resource of the DGW caused because theDGW buffers data for a long time can be avoided, and a network resourceis effectively used.

609. The CGW stops timing of the first timer, and sends the routinginformation of the base station to the DGW.

If the CGW has received, before the first timer expires, in other words,within the timed duration of the first timer, the routing information ofthe base station sent by the MME, the CGW stops timing of the firsttimer, and sends the routing information of the base station to the DGWby using the S18 interface.

610. The DGW stops timing of the second timer, and sends the buffereddownlink data packet and the buffered subsequently received downlinkdata packet to the UE based on the routing information of the basestation.

The DGW establishes the corresponding bearer based on the routinginformation of the base station sent by the CGW, and sends the buffereddownlink data packet and the buffered subsequently received downlinkdata packet to the base station by using the corresponding bearer, andthe base station sends the received downlink data packet to the UE.

611. The CGW sends the DDN message to the MME when the first time periodexpires, and sends a third indication message to the DGW.

If the CGW has not received the routing information of the base stationwithin the first time period, the CGW sends the DDN message to the MMEwhen the first time period expires, to trigger the MME to page the UE,so that the UE performs the service request procedure shown in FIG. 5.The CGW further sends the third indication message to the DGW, and thethird indication message is used to instruct the DGW to stop timing ofthe second timer and discard the buffered downlink data packet and thebuffered subsequently received downlink data packet.

612. The DGW stops timing of the second timer and discards the buffereddownlink data packet and the buffered subsequently received downlinkdata packet based on the third indication message.

613. The CGW sends the DDN message to the MME.

In the technical solution of this embodiment of the present invention,on one hand, when the downlink data packet sent to the UE and receivedby the DGW matches no bearer, the DGW may buffer the downlink datapacket based on the idle-state UE data buffering mechanism, and send thereported event and the identifier information to the CGW, so that theCGW determines whether the UE is registered in the MME that sends thedelay instruction to the CGW, thereby lowering processing complexity ofthe DGW. On the other hand, after receiving the reported event and theidentifier information that are sent by the DGW, the CGW can determine,based on the identifier information and the locally stored contextinformation of the UE, whether the UE corresponding to the downlink datapacket is registered in the MME that sends the delay instruction to theCGW, and if the UE is registered in the MME, the CGW delays sending theDDN message to the MME, so that unnecessary DDN sending can be reduced,and signaling load of the MME can be reduced.

FIG. 7A and FIG. 7B are a schematic flowchart of still another DDNmessage sending method according to an embodiment of the presentinvention. In the method shown in FIG. 7A and FIG. 7B, a DGW does notuse an idle-state UE data buffering mechanism, but a CGW uses theidle-state UE data buffering mechanism. For other content similar tothat in the method shown in FIG. 6, refer to the detailed description inFIG. 6, and details are not described herein again. As shown in FIG. 7Aand FIG. 7B, the method includes the following steps.

701 and 702 are respectively similar to 601 and 602 in the method shownin FIG. 6. For details, refer to the detailed descriptions in 601 and602, and details are not described herein again.

703. The DGW sends an event report message to the CGW, where the eventreport message includes the downlink data packet and a reported event,and the reported event is used to notify the CGW that the downlink datapacket sent to the UE matches no bearer.

In an example, the event report message further includes identifierinformation, and the identifier information is used to determine thatthe downlink data packet is sent to the UE. For specific descriptions ofthe identifier information, refer to the detailed description in 604,and details are not described herein again.

704. The CGW determines whether the UE is registered in the MME sendingthe delay instruction; and if determining that the UE is registered inthe MME, performs step 705; or if determining that the UE is notregistered in the MME, performs step 715.

If the event report message carries the identifier information, the CGWmay determine, based on the identifier information and locally storedcontext information of the UE, whether the UE is registered in the MMEinstructing to delay sending the DDN message. A specific implementationis similar to that in 605, and for details, refer to the detaileddescription in 605. If the event report message does not carry theidentifier information, the CGW may determine, based on a destinationaddress of the downlink data packet and locally stored contextinformation of the UE, the UE corresponding to the received downlinkdata packet, and further determine whether the corresponding UE isregistered in the MME sending the delay instruction, so as to determinewhether the CGW needs to delay sending the DDN message. The destinationaddress of the downlink data packet may be an IP address of the UE.

705. The CGW buffers the downlink data packet, and starts a third timer,where timed duration is a first time period.

Duration of the first time period may be duration represented by onedelay parameter, or may be duration of a sum of a plurality of delayparameters. In other words, after the CGW sets the third timer based onthe delay parameter, if the third timer expires, and the CGW has notreceived routing information of a base station, the CGW may furtherrestart the third timer, and set the timed duration to the durationindicated in the delay parameter.

706. The CGW determines whether a service type of the UE is a presettype; and if the service type is the preset type, performs step 707; orif the service type is not the preset type, performs step 709.

There may be a plurality of service types, for example, a voice service,a video service, and a short message service. The preset type may be avideo service, or may be another preset service. This is not limited inthis application. For a video service, a loss of a data packetcorresponding to the video service causes relatively small impact touser experience. In this case, a fourth indication message may be usedto instruct the DGW to: discard a subsequently received downlink datapacket, and continue to send a downlink data packet when the UE is in aconnected state. For a voice service, a short message service, and thelike, losses of data packets corresponding to the voice service and theshort message service cause relatively great impact to user experience.In this case, a fourth indication message may be used to instruct theDGW to start a fourth timer to buffer a subsequently received downlinkdata packet.

707. The CGW sends a fourth indication message including a discardinginstruction to the DGW, where the fourth indication message is used toinstruct the DGW to discard a subsequently received downlink datapacket.

708. The DGW discards the subsequently received downlink data packet.

In an example, after the CGW sends the discarding instruction to theDGW, when receiving another downlink data packet of a current service ofthe UE, the DGW directly discards the downlink data packet, in otherwords, the DGW does not use a buffering mechanism. In this case, whenthe DGW receives a downlink data packet of the UE, the DGW may add thedownlink data packet to the event report message and send the eventreport message to the CGW, so that the CGW buffers a subsequentlyreceived downlink data packet based on the local third timer of the CGW.

709. The CGW sends a fourth indication message including the first timeperiod to the DGW, where the fourth indication message is used by theDGW to start a fourth timer and configure timed duration of the fourthtimer to the first time period.

710. The DGW starts the fourth timer, configures the timed duration ofthe fourth timer to the first time period, and buffers a subsequentlyreceived downlink data packet within the timed duration of the fourthtimer.

The DGW starts the fourth timer based on the fourth indication message,and if receiving a downlink data packet of the UE subsequently, buffersthe subsequently received downlink data packet.

711. The CGW determines whether routing information of a base stationhas been received within the first time period; and if the routinginformation has been received, performs step 712; or if the routinginformation has not been received, performs step 714.

712. The CGW stops timing of the third timer, and sends the routinginformation of the base station and the buffered downlink data packet tothe DGW.

713. The DGW stops timing of the fourth timer, and sends the buffereddownlink data packet and the buffered subsequently received downlinkdata packet to the UE based on the routing information of the basestation.

714. The CGW discards the buffered downlink data packet, sends a fifthindication message to the DGW, and sends the DDN message to the MME whenthe first time period expires, where the fifth indication message isused to instruct the DGW to discard the buffered subsequently receiveddownlink data packet.

715. The DGW stops timing of the fourth timer and discards the bufferedsubsequently received downlink data packet based on the fifth indicationmessage.

716. The CGW sends the DDN message to the MME, to trigger the MME topage the UE, so that the UE initiates a service request procedure.

For content in 709 to 716 similar to that in 606 to 613 in the methodshown in FIG. 6, refer to the detailed descriptions in 606 to 613, anddetails are not described herein again.

In the technical solution of this embodiment of the present invention,on one hand, when the downlink data packet sent to the UE and receivedby the DGW matches no bearer, the DGW may send the reported event, thedownlink data packet, and the identifier information to the CGW, so thatthe CGW determines whether the UE is registered in the MME that sendsthe delay instruction to the CGW, thereby lowering processing complexityof the DGW. On the other hand, after receiving the reported event, thedownlink data packet, and the identifier information that are sent bythe DGW, the CGW can determine, based on the identifier information andthe locally stored context information of the UE, whether the UEcorresponding to the downlink data packet is registered in the MME thatsends the delay instruction to the CGW, and if the UE is registered inthe MME, the CGW delays sending the DDN message to the MME, so thatunnecessary DDN sending can be reduced, and signaling load of the MMEcan be reduced.

It should be noted that the methods in FIG. 5 to FIG. 7A and FIG. 7B mayalso be applied to the network architecture shown in FIG. 3. When themethods are applied to the network architecture shown in FIG. 3,functions of the CGW may be implemented by using an SGW-C or a PGW-C,and functions of the DGW may be implemented by using an SGW-U or aPGW-U. For a specific implementation process, refer to the detaileddescriptions in the methods shown in FIG. 5 to FIG. 7A and FIG. 7B, anddetails are not described herein again.

The foregoing mainly describes, from the perspective of interactionbetween network elements, the solutions provided in the embodiments ofthe present invention. It may be understood that to implement theforegoing functions, the network elements, for example, the controlplane network element and the user plane network element, includecorresponding hardware structures and/or software modules for executingthe functions. A person skilled in the art should be easily aware thatunits and algorithm steps of the examples described with reference tothe embodiments disclosed in this specification can be implemented byhardware or a combination of hardware and computer software in thepresent invention. Whether a function is performed by hardware or bycomputer software driving hardware depends on a particular applicationand design constraint condition of the technical solutions. Aprofessional technician may implement the described function forparticular applications by using different methods. However, thisimplementation should not be construed beyond the scope of the presentinvention.

FIG. 8 is a schematic structural diagram of a control plane networkelement included in the foregoing embodiments. The control plane networkelement may be a CGW in the network architecture shown in FIG. 2, or maybe an SGW-C or a PGW-C in the network architecture shown in FIG. 3.

The control plane network element includes a controller/processor 802,configured to control and manage actions of the control plane networkelement. For example, the controller/processor 802 is configured tosupport the control plane network element in performing the processes401, 404, 405, and 406 in FIG. 4, the process 503 in FIG. 5, theprocesses 601, 605, 606, 608, 609, 611, and 613 in FIG. 6, the processes701, 704, 705, 706, 707, 709, 711, 712, 714, and 716 in FIG. 7A and FIG.7B, and/or other processes of the technology described in theembodiments of the present invention. A memory 801 is configured tostore program code and data used for the control plane network element.A network interface 803 is configured to support communication betweenthe control plane network element and another network entity. Forexample, the network interface 803 is configured to supportcommunication between the control plane network element and the userplane network element in FIG. 9. For another example, the networkinterface 803 is configured to support communication between the controlplane network element and each network entity shown in FIG. 2 or FIG. 3.

FIG. 9 is a schematic structural diagram of a user plane network elementincluded in the foregoing embodiments. The user plane network elementmay be a DGW in the network architecture shown in FIG. 2, or may be anSGW-U or a PGW-U in the network architecture shown in FIG. 3.

The user plane network element includes a controller/processor 902,configured to control and manage actions of the user plane networkelement. For example, the controller/processor 902 is configured tosupport the user plane network element in performing the processes 402and 403 in FIG. 4, the process 503 in FIG. 5, the processes 602, 603,604, 607, 610, and 612 in FIG. 6, the processes 702, 703, 708, 710, 713,and 715 in FIG. 7A and FIG. 7B, and/or other processes of the technologydescribed in the embodiments of the present invention. A memory 901 isconfigured to store program code and data used for the user planenetwork element. A network interface 903 is configured to supportcommunication between the user plane network element and another networkentity. For example, the network interface 903 is configured to supportcommunication between the user plane network element and the controlplane network element in FIG. 8. For another example, the networkinterface 903 is configured to support communication between the userplane network element and each network entity shown in FIG. 2 or FIG. 3.

The controller/processor configured to execute functions of the controlplane network element or the user plane network element in the presentinvention may be a central processing unit (CPU), a general purposeprocessor, a digital signal processor (DSP), an application-specificintegrated circuit (ASIC), a field programmable gate array (FPGA) oranother programmable logic device, a transistor logic device, a hardwarecomponent, or any combination thereof. The controller/processor mayimplement or execute examples of various logical blocks, modules, andcircuits described in the content disclosed in the present invention.The processor may be a combination implementing a computing function,for example, a combination including one or more microprocessors, or acombination of a DSP and a microprocessor.

The methods or algorithm steps that are described with reference to thecontent disclosed in the present invention may be implemented in ahardware manner, or may be implemented in a manner of executing asoftware instruction by a processor. The software instruction mayinclude a corresponding software module. The software module may bestored in a random access memory (RAM), a flash memory, a read-onlymemory (ROM), an erasable programmable read-only memory (EPROM), anelectrically erasable programmable read-only memory (EEPROM), aregister, a hard disk, a removable hard disk, a compact disc read-onlymemory (CD-ROM), or a storage medium in any other forms well-known inthe art. A storage medium used as an example is coupled to theprocessor, so that the processor can read information from the storagemedium, and can write information into the storage medium. Certainly,alternatively, the storage medium may be a part of the processor. Theprocessor and the storage medium may be located in an ASIC. In addition,the ASIC may be located in the control plane network element or the userplane network element. Certainly, the processor and the storage mediummay also exist in the control plane network element or the user planenetwork element as discrete components.

A person skilled in the art should be aware that in one or more of theforegoing examples, the functions described in the present invention maybe implemented by using hardware, software, firmware, or any combinationthereof. When the functions are implemented by software, these functionsmay be stored in a computer-readable medium or transmitted as one ormore instructions or code in the computer-readable medium. Thecomputer-readable medium includes a computer storage medium and acommunications medium, where the communications medium includes anymedium that enables a computer program to be transmitted from one placeto another. The storage medium may be any available medium accessible toa general or dedicated computer.

The objectives, technical solutions, and benefits of the presentinvention are further described in detail in the foregoing specificembodiments. It should be understood that the foregoing descriptions aremerely specific embodiments of the present invention, but are notintended to limit the protection scope of the present invention. Anymodification, equivalent replacement, or improvement made based on thetechnical solutions of the present invention shall fall within theprotection scope of the present invention.

The invention claimed is:
 1. A method comprising: receiving, by acontrol plane network element, a delay indication from a mobilitymanagement network element, wherein the delay indication indicatesdelaying sending a downlink data notification message by the controlplane network element to the mobility management network element;receiving, by a user plane network element, a downlink data packet to besent to a user equipment (UE); and in response to that the downlink datapacket matches no bearer, sending, by the user plane network element, anevent report message to the control plane network element, wherein theevent report message comprises a reported event, and the reported eventnotifies the control plane network element that the downlink data packetmatches no bearer; upon receiving the event report message, determining,by the control plane network element, that the UE is registered in themobility management network element; and in a case that the controlplane network element has not received routing information of a basestation from the mobility management network element within a first timeperiod, sending, by the control plane network element, a first downlinkdata notification message corresponding to the downlink data packet tothe mobility management network element, wherein the routing informationof the base station identifies a bearer.
 2. The method according toclaim 1, wherein the event report message further comprises identifierinformation, and wherein the identifier information is used to determinethat the downlink data packet is for the UE.
 3. The method according toclaim 1, wherein after receiving, by the user plane network element, thedownlink data packet for the UE, the method further comprise: starting,by the user plane network element, a timer, wherein a timed duration ofthe timer is a second time period; and buffering the downlink datapacket within the timed duration of the timer.
 4. The method accordingto claim 3, wherein before receiving, by the user plane network element,the downlink data packet for the UE, the method further comprise:receiving, by the user plane network element, a second indicationmessage from the control plane network element, wherein the secondindication message indicates configuring the timed duration of the timerto the second time period by the user plane network element.
 5. Themethod according to claim 2, wherein determining, by the control planenetwork element, that the UE is registered in the mobility managementnetwork element comprises: determining, based on the identifierinformation, that the UE is registered in the mobility managementnetwork element.
 6. The method according to claim 2, whereindetermining, by the control plane network element, that the UE isregistered in the mobility management network element comprises:determining, based on the identifier information and locally storedcontext of the UE, that the UE is registered in the mobility managementnetwork element.
 7. A communications system comprising: a user planenetwork element and a control plane network element; and wherein theuser plane network element is configured to: receive a downlink datapacket to be sent to a user equipment (UE), and in response to that thedownlink data packet matches no bearer, send an event report message tothe control plane network element, wherein the event report messagecomprises a reported event, and the reported event notifies the controlplane network element that the downlink data packet matches no bearer,and wherein the control plane network element is configured to: receivea delay indication from a mobility management network element, whereinthe delay indication indicates delaying sending a downlink datanotification message by the control plane network element to themobility management network element, receive the event report messagefrom the user plane network element, upon receiving the event reportmessage, determine that the UE is registered in the mobility managementnetwork element, and in a case that the control plane network elementhas not received routing information of a base station from the mobilitymanagement network element within a first time period, send a firstdownlink data notification message corresponding to the downlink datapacket to the mobility management network element, wherein the routinginformation of the base station identifies a bearer.
 8. Thecommunications system according to claim 7, wherein the event reportmessage further comprises identifier information, and the identifierinformation is used to determine that the downlink data packet is forthe UE.
 9. The communications system according to claim 8, wherein thecontrol plane network element is configured to determine, based on theidentifier information, that the UE is registered in the mobilitymanagement network element.
 10. The communications system according toclaim 8, wherein the control plane network element is configured todetermine, based on the identifier information and locally storedcontext of the UE, that the UE is registered in the mobility managementnetwork element.
 11. A method comprising: receiving, by a control planenetwork element, a delay indication from a mobility management networkelement, wherein the delay indication indicates delaying sending adownlink data notification message by the control plane network elementto the mobility management network element; receiving, by the controlplane network element, an event report message from a user plane networkelement, wherein the event report message comprises a reported event,and the reported event notifies the control plane network element that adownlink data packet to be sent to user equipment (UE) matches nobearer; upon receiving the event report message, determining, by thecontrol plane network element, that the UE is registered in the mobilitymanagement network element; and in a case that the control plane networkelement has not received routing information of a base station from themobility management network element within a first time period, sending,by the control plane network element, a first downlink data notificationmessage corresponding to the downlink data packet to the mobilitymanagement network element, wherein the routing information of the basestation is used to identify a bearer.
 12. The method according to claim11, wherein the event report message further comprises identifierinformation, and the identifier information is used to determine thatthe downlink data packet is for the UE.
 13. The method according toclaim 12, wherein determining, by the control plane network element,that the UE is registered in the mobility management network elementcomprises: determining, based on the identifier information, that the UEis registered in the mobility management network element.
 14. The methodaccording to claim 12, wherein the determining, by the control planenetwork element, that the UE is registered in the mobility managementnetwork element comprises: determining, by the control plane networkelement, based on the identifier information and locally stored contextof the UE, that the UE is registered in the mobility management networkelement.
 15. A control plane network element comprising: a processor anda memory, wherein the processor is coupled to the memory and configuredto execute instructions stored in the memory, and the instructions, whenexecuted by the processor, cause the control plane network element to:receive a delay indication from a mobility management network element,wherein the delay indication indicates delaying sending a downlink datanotification message by the control plane network element to themobility management network element; receive an event report messagefrom a user plane network element, wherein the event report messagecomprises a reported event, and the reported event notifies the controlplane network element that a downlink data packet to be sent to userequipment (UE) matches no bearer; upon receiving the event reportmessage, determine that the UE is registered in the mobility managementnetwork element; and in a case that the control plane network elementhas not received, within a first time period, routing information of abase station from the mobility management network element, send a firstdownlink data notification message corresponding to the downlink datapacket to the mobility management network element, wherein the routinginformation of the base station is used to identify a bearer.
 16. Thecontrol plane network element according to claim 15, wherein the eventreport message further comprises identifier information, and theidentifier information is used to determine that the downlink datapacket is for the UE.
 17. The control plane network element according toclaim 16, wherein the instructions, when executed by the processor,further cause the control plane network element to determine, based onthe identifier information, that the UE is registered in the mobilitymanagement network element.
 18. The control plane network elementaccording to claim 16, wherein the instructions, when executed by theprocessor, further cause the control plane network element to:determine, based on the identifier information and locally storedcontext of the UE, that the UE is registered in the mobility managementnetwork element.